Stiffness based in-situ assessment of static recrystallization kinetics for cold-rolled aluminum alloys

Static recrystallization (SRX) plays a crucial role in the processing of cold-rolled aluminum alloys, as it strongly affects key material properties and occurs during various heat treatments along the processing route. However, the characterization of SRX kinetics by established methods is costly and complex. The analysis of the relation between the recrystallization kinetics and the influence of alloying elements, dislocation density and temperature is elaboratory. To overcome this issue, a novel approach is introduced, allowing to assess the recrystallization kinetics from the evolution of the material stiffness measured by the impulse excitation technique (IET) at remarkably high efficiency. Due to the formation of recrystallized grains, the orientation distribution of the polycrystal changes. Consequently, the anisotropic elastic behavior on macroscopic scale changes, which is reflected in the macroscopic elastic properties. Absolute changes in directional Young's moduli between 0.5 GPa and 2.0 GPa during annealing processes up to 70 h are observed via in-situ IET measurements at high accuracy, allowing to characterize the recrystallization kinetics. The proposed method is exemplarily applied to AA 1050 processed by cold rolling. Complementary analyses by applying electron backscatter diffraction (EBSD) or by analyzing the evolution of the yield strength are conducted to verify the described method. • In-situ characterization of static recrystallization kinetics via texture evolution observed through the evolution of the materials stiffness. • Static recrystallization of cold-rolled sheets results in a decrease in Young's moduli along the rolling and transverse directions, while causing an increase along the diagonal direction. • The evolutions of directional Young's moduli are captured at high precision in-situ during recrystallization from the eigenfrequencies of a specimen using the impulse excitation technique. • Elucidation of stiffness evolution during recrystallization by texture measurements using EBSD. • The impulse excitation technique allows to characterize recrystallization kinetics in an economical, efficient and reliable way.